Implementation of computer-based wireless communication devices, including wireless local area networks (LANs) and wireless ready systems is a quickly emerging and evolving technology. Conventional computer-based wireless communication devices transmit radio frequency (RF) signals to wireless receivers of LANs. These devices include transmitters that both transmit and receive wireless communication within a particular bandwidth in the highly regulated RF spectrum.
The RF spectrum is a limited bandwidth spectrum that is allocated among a number of different services types/applications, including military, aviation, broadcast, and commercial communications. Because of the very limited bandwidth available within the RF spectrum, transmission in this medium is subject to strict government regulations. The regulations typically cover the type and parameters of the transmitters being utilized in a wireless network. These regulations cover modulation scheme, frequency of operation, and transmit power of the transmitters in order to avoid interference among the various authorized services utilizing the RF spectrum.
Transmitters comprise a combination of a circuit module called a radio coupled to an antenna. The antenna is a central part of the transmitter since the antenna is designed and tuned to optimize gain or attenuation for desired frequencies. Conventionally, manufacturers of transmitters obtain a license from the government authorizing the manufacturer to manufacture a particular type of transmitter, exhibiting particular parameters. The license covers both components of the transmitter unit (i.e., radio and antenna), and the license typically specifies exact protocols (i.e., operating parameters or ranges of parameters) for both components and the combination device. In the United States, for example, licenses are granted and regulated by the Federal Communication Commission (FCC). Also, the regulations require that the end users not be able to change or reconfigure the transmitter, which would result in operation outside of the authorized parameters. Any change made to the operating parameters, radio or antenna requires another application for license and authorization by the FCC.
It is essential for wireless LANs, such as those operating under the 801.11b and 802.11a frequency ranges, that they operate within authorized parameters. The IEEE 802.11b specification defines the allowable frequency bands (or channels) in which the transmitter may operate. However, on a worldwide basis, each country may only allow a subset of this spectrum to be utilized so as to avoid interference with country specific restricted bands, such as illustrated in FIG. 3. For example, in Japan, the IEEE specifications permit transmissions within all fourteen bands (See FIG. 2), and the Japanese government also permits operation within all of these fourteen bands. The European Union is slightly different in that the IEEE specifications and the government regulations do not permit transmissions within the fourteenth channel. As can be seen in FIGS. 2 and 3, the U.S. government permits transmissions within the first thirteen bands, while the IEEE specification only permits transmission within the first eleven bands.
For example, if the U.S. or European Union allow channel 14 or the IEEE changes the specification to allow 802.11b operation on channels 12 or 13 in the U.S., then it would be expected that access points operating on the additional channels would soon be available in the market. Most of the wireless cards would passively scan channels 1-14 and detect access points on channels 12 or 13. After detection of the access points on channels 12 or 13, the wireless cards would associate with the access points. However, this would violate the grant of authorization for the wireless card. In the U.S., this would be a violation of the FCC authorization for that particular wireless card.